Isolation, purification, and structural elucidation of Stropharia rugosoannulata polysaccharides with hypolipidemic effect

Abstract

<i>Stropharia rugosoannulata</i> is a widely grown edible mushroom with a high nutritional value. <i>S. rugosoannulata</i> polysaccharides is one of the most important bioactive components of <i>S. rugosoannulata</i> and has a wide range of activities. A <i>S. rugosoannulata</i> polysaccharides, named SRF-3, was derived from the <i>S. rugosoannulata</i> extraction by freeze-thaw combine with hot water extraction method, then prepareed with DEAE-cellulose column and Sephacryl S-200 HR gel column, and its hypolipidemic activity was determined. The structural characteristics of SRF-3 were analyzed by infrared spectral scanning (FT-IR), ultra-high performance liquid chromatography (UHPLC), acid hydrolysis, methylation analysis, nuclear magnetic resonance (NMR), and Gas Chromatography-Mass Spectrometer (GC-MS). SRF-3 is composed of mannose, galactose, methyl galactose and fructose with ratios of 16, 12, 58 and 12, respectively. In addition, the average relative molecular mass of SRF-3 is approximately 24 kDa. The main chain of SRF-3 is mainly composed of repeating α-D-1,6-Gal<i>p</i> and α-D-1,6-Me-Gal<i>p</i> units, with branches in the O-2 position of Gal. The structure is presumed to be a mannogalactan, with a small amount of t-β-D-Man<i>p</i> present as a side chain. Hypolipidemic activity assay showed that SRF-3 had good antioxidant and hypolipidemic effects <i>in vitro</i>, suggesting that SRF-3 have potential application in reducing liver fat accumulation.